Cyperus surinamensis |
Cyperus pilosus |
|
---|---|---|
tropical flatsedge |
fuzzy flatsedge |
|
Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | Herbs, annual or perennial, cespitose; stolons slender, to 5 cm × 1.5 mm. |
Culms | 2–6, trigonous, (10–)35–80 cm × 0.5–2(–4) mm, scabridulous with retrorse prickles (infrequently glabrous or rarely also with extrorse prickles). |
trigonous, 25–90 cm × 2 mm, hispidulous or glabrous on angles distally. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
flat, 10–35 cm × 3–10 mm. |
Inflorescences | heads umbellate, 10–20(–30) mm diam.; rays 4–12, 1–6 cm, minutely scabridulous with retrorse prickles; 2d order rays often present, 1–2(–3) cm; 3d order rays rarely present, 0.5–1.5 cm; bracts 3–8, approximately horizontal to ascending at 30°, V-shaped to flat, 2–15(–34) cm × 1–4(–5) mm. |
spikes 1–4(–6), loosely oblong-ovoid, 2–3 × 1–2 cm; rays 3–10, 1–16 cm; 2d order rays to 3 cm; rachis hispidulous, prickles slender, 0.1–0.2 mm; bracts 3–5, ± ascending, flat, 5–35 cm × 0.5–5(–7) mm; rachilla persistent, wingless. |
Spikelets | (6–)15–40(–65), greenish white, linear to linear-oblong, (3–)4–12(–15) × 1.5–2.5 mm; floral scales 10–50(–65), laterally pale yellow, light brown, or reddish brown, 2-keeled, medially 3-ribbed, lanceolate, 1–1.5 × 0.8–0.9 mm, distinctly reticulate, often scabridulous near apex. |
15–40, linear-lanceoloid, compressed, 6–12 × 1.5–2 mm; floral scales deciduous, 8–16, light brown with clear border, laterally 2–3-ribbed, ovate, 1.8–2 × 1.2–1.6 mm; apex entire, emarginate, or mucronulate, mucro at most 0.3 mm. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
anthers 0.4 mm; styles 0.6 mm; stigmas 1 mm. |
Achenes | brown to reddish brown, slightly stipitate, narrowly ellipsoid, 0.7–0.9 × 0.2–0.4 mm, apex apiculate, surfaces papillate or obscurely reticulate to rugulose. |
brown, sessile, broadly ellipsoid, 1–1.2 × 0.5 mm, apex obtuse, apiculate, surfaces puncticulate. |
Cyperus surinamensis |
Cyperus pilosus |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer. |
Habitat | Moist sunny areas with disturbed soils | Rice fields, wetlands, emergent muddy shores |
Elevation | 0–200 m (0–700 ft) | 0–50 m (0–200 ft) |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
|
FL; LA; MS; SC; Asia [Introduced in North America]
|
Discussion | Cyperus surinamensis is distinguished readily from all other species of the genus in the New World by the usual presence of retrorse prickles on the culms and rays. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus pilosus was naturalized in the flora from eastern Asia, apparently early in the twentieth century. The combination of hispidulous rachis and loosely oblong-ovoid spikes is sufficient to distinguish Cyperus pilosus from any others with deciduous floral scales. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 166. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Vahl: Enum. Pl. 2: 354. (1805) |
Web links |